Page 1671 - Saunders Comprehensive Review For NCLEX-RN

depressed ST segments.
3. A high magnesium level can cause muscle weakness,
hypotension, and bradycardia.
4. Electrocardiographic changes that may be observed
with hypermagnesemia include a prolonged PR
interval and widened QRS complex.

Electrolyte and mineral imbalances can cause cardiac

electrical instability that can result in life-threatening dysrhythmias.
L. Blood urea nitrogen: The blood urea nitrogen level is elevated in
heart disorders such as heart failure and cardiogenic shock that
reduce renal circulation.
M. Blood glucose: An acute cardiac episode can elevate the blood
glucose level.
N. B-type natriuretic peptide (BNP)

1. BNP is released in response to atrial and ventricular
stretch; it serves as a marker for heart failure.
2. BNP levels should be less than 100 ng/mL (less than
100 mcg/L); the higher the level, the more severe the
heart failure.
O. Chest x-ray
1. Description: Radiography of the chest is done to
determine anatomical changes such as the size,
silhouette, and position of the heart.
2. Interventions
a. Prepare the client, explaining the
purpose and procedure.
b. Remove jewelry.
c. Ensure that the client is not pregnant.
P. Electrocardiography (Box 52-1)
1. Description: This common noninvasive diagnostic test
records the electrical activity of the heart and is useful
for detecting cardiac dysrhythmias, location and
extent of MI, and cardiac hypertrophy, and for
evaluation of the effectiveness of cardiac medications.
2. Interventions
a. Determine the client’s ability to lie still; advise the
client to lie still, breathe normally, and refrain from
talking during the test.
b. Reassure the client that an electrical shock will not
occur.
c. Document any cardiac medications the client is taking.
Q. Holter monitoring
1. Description
a. A noninvasive test; the client wears a

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